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Joomla CMS CVE-2026-92225

| EUVDEUVD-2026-89075 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-09-29 Joomla GHSA-vfpr-256v-f8j4
5.9
CVSS 4.0 · Vendor: Joomla
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate to Joomla backend with privileged account
  2. Delivery
    Inject unescaped payload into module-list field
  3. Exploit
    Victim admin opens module list
  4. Execution
    Script executes in admin session
  5. Impact
    Hijack session / act as administrator

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires an authenticated Joomla backend user with sufficient privileges to supply/store values rendered by the module list layout (PR:H), and passive interaction from a victim who views that module list (UI:P). It affects Joomla Core 4.0.0-5.4.8 and 6.0.0-6.1.3. Limiting factors: exploitation is confined to the administrative backend and needs an existing privileged account, so it cannot be triggered by anonymous internet users against a default front-end; the payload only fires when another user renders the unescaped module-list layout.

Impact

This is a moderate-priority, not a top-tier, issue. The CVSS 4.0 base score is 5.9 (medium) with vector AV:N/AC:L/AT:N/PR:H/UI:P - network reachable and low complexity, but gated by PR:H (high privileges) meaning the attacker already needs an authenticated Joomla backend/administrator account with access to the module manager, plus passive user interaction (UI:P) from a victim viewing the affected module-list layout. The E:U (Exploit: Unproven) temporal signal, the absence of any EPSS score, no CISA KEV listing, and no public POC all point to no known exploitation and no imminent widespread-exploit pressure. There is a tension worth flagging: the vendor's 4.0 vector rates VC:H/VI:H (high confidentiality and integrity impact) for what the description characterizes as a single XSS vector in an admin layout - for a stored/reflected XSS the concrete impact is typically limited (session/token theft, admin-context script execution), so those H ratings look aggressive and should be verified against the Joomla advisory. Net: a real bug worth patching, but its PR:H prerequisite and admin-only surface make it far lower real-world risk than an unauthenticated Joomla flaw.

Exploit ScenarioDerived

An attacker who already holds a privileged Joomla backend account (or a lower-privileged user granted module-management rights) stores a crafted value that is rendered unescaped in the module list layout. When another administrator subsequently opens the module list, the injected script executes in their authenticated backend session, enabling session/token theft or actions in the victim admin's context. No public exploit code has been identified at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 29, 2026

Stored cross-site scripting in the Joomla CMS module list layout allows an authenticated administrator-level backend user to supply values that are rendered without escaping, so script executes in the browser of another privileged user who views the module list. Affected releases are Joomla CMS 4.0.0 through 5.4.8 and 6.0.0 through 6.1.3, and the vendor-assigned CVSS 4.0 base score is 5.9. Because exploitation requires a pre-existing high-privilege account (PR:H) and a victim who opens the affected administrative view (UI:P), the issue is confined to the backend and cannot be triggered by anonymous front-end visitors; no public exploit code and no CISA KEV entry are associated with this CVE at time of analysis, and a vendor advisory covering the fixed releases is available from the Joomla Security Centre.

RemediationAI

Apply the fixed release documented in Joomla Security Centre advisory 20260912 (https://developer.joomla.org/security-centre/1092-20260912-core-xss-in-module-list.html) by upgrading to the current patched version on the 5.x or 6.x branch, since 5.4.8 and 6.1.3 are the last affected releases in each line - patch available per vendor advisory, exact fixed version not independently confirmed from the supplied data. If the upgrade cannot be scheduled immediately, cut exposure by restricting who can reach /administrator (IP allowlisting or an HTTP authentication layer in front of the backend) and by enforcing least privilege so only trusted accounts hold the module-management permissions needed to plant the payload; the trade-off is that these are access controls that depend on disciplined account hygiene and do not correct the underlying encoding defect. Adding a strict Content-Security-Policy for the administrative backend (via web server configuration or a Joomla security-headers plugin) or a WAF rule blocking inline script in backend responses reduces the likelihood of successful execution but leaves the vulnerable code path intact, and simply disabling the module list layout is impractical for most administrators. As a detection measure, audit backend accounts and review stored module records for unexpected markup.

Affected VersionsENISA

Joomla! CMS 4.0.0-5.4.8
Joomla! CMS 6.0.0-6.1.3

Affected Packages

euvd joomla_cms no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The root cause is CWE-79, improper neutralization of input during web page generation (cross-site scripting). The flaw lies in Joomla's core module list layout in the administrative backend, where user-supplied values were written into the generated HTML without appropriate output encoding, so markup or script stored by one backend user is later rendered in another user's browser session. Joomla component MVC layouts normally funnel values through escaping helpers before output; this layout bypassed that neutralization, converting an ordinary data field into an injection point. The affected code is Joomla CMS core itself (CPE cpe:2.3:a:joomla!_project:joomla!_cms), not a third-party extension, so every site on the affected branches ships the vulnerable code, although reaching the vulnerable view requires backend privileges. The vendor's CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:L) and our independent CVSS 3.1 assessment (AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N) agree on the network attack vector, high privilege prerequisite, and required user interaction; our assessment characterizes confidentiality and integrity impact as low with changed scope, consistent with script execution constrained to an authenticated administrative context rather than a broadly reachable front-end attack surface.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (Joomla) PRIMARY 5.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:U
vuln.today AI 4.8 MEDIUM

Backend-only XSS needs a privileged authenticated account (PR:H) and a victim rendering the page (UI:R); browser-context execution crosses a trust boundary (S:C) with limited confidentiality/integrity impact (C:L/I:L), no availability impact.

3.1 AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Primary rating from Vendor (Joomla).

CVSS VectorVendor: Joomla

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
High
User Interaction
Passive
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
High
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

Joomla! Core - [20260912] - Core - XSS in module list in Joomla 4.0.0-5.4.8, 6.0.0-6.1.3 - The module list layout did not properly escape user supplied values, leading to an XSS vector.

Threat Intelligence Overview

EPSS Score
0.3%
Top 84% exploitable
Prevalence
High
Joomla is one of the most widely deployed open-source CMS platforms
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
High
Technical Impact
Total

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

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